1. Field of the Invention
The present invention relates to an image pickup apparatus and a control method therefor.
2. Description of the Related Art
Conventionally, in film production, to achieve special video effects, filming is performed while changing the speed of filming with a film camera, that is, changing the number of frames per second. For example, when filming is performed faster than normal speed, and when playback operation is performed at normal speed, slow-motion playback images can be obtained. With this technique, high speed operation, such as a scene in which droplets are falling onto a water surface, can be easily and meticulously observed. Conversely, when filming is performed slower than normal speed, and when playback operation is performed at normal speed, fast-motion playback images can be obtained. With this technique, a sense of speed in, for example, battle scenes or car chase scenes, can be increased so that the scenes become more realistic and have a greater impact.
In television program production, imaging, editing, and transmission of programs is being digitized. Due to the development of digital technologies, the image quality is becoming higher and the cost of devices for producing programs is becoming lower. Digitization of film production is also improving.
Because of the digitization of television programs or film production, when imaging with an image pickup apparatus (video camera), the frame rate can be changed to easily obtain special video effects, for example, fast-motion playback operation or slow-motion playback operation. Such an image pickup apparatus is disclosed in, for example, Japanese Unexamined Patent Application Publication No. 2000-125210. When imaging at a frame rate lower than a predetermined frame rate by using this image pickup apparatus and when performing playback at the predetermined frame rate, fast-motion playback images can be easily obtained. In contrast, when imaging at a frame rate higher than a predetermined frame rate and when performing playback at the predetermined frame rate, slow-motion playback images can be easily obtained.
A camera controller or a signal recorder can be connected to an image pickup apparatus. In this case, part of the operation of the image pickup apparatus, for example, signal processing, such as γ correction, can sometimes be controlled not only by an operator using the image pickup apparatus but also by the camera controller or the signal recorder. It is now assumed that the frame rate of the image pickup apparatus can be controlled by the camera controller or the signal recorder. In this case, monitor images displayed on an image display device, for example, an electronic viewfinder or a monitor device, connected to or provided for the image pickup apparatus are not always controlled at a frame rate suitable for the operator to check the images that are being captured. For example, when a fast moving subject is imaged, the frame rate is decreased. In this case, if the frame rate of monitor images is also decreased, the interval for updating the monitor images becomes long, thereby making it difficult for the operator to properly image while following the subject.